I'm seeing indications that this is sometimes related to language translation using GTranslate.io [1]

> We use XNUMX variable instead of all numbers in our edit interface. For example "10 cents" in your original text is represented as "XNUMX cents" in the edit interface, so if you translate "XNUMX cents" once, the same translation will be used for all similar phrases like "11 cents", "18 cents", etc. This helps to do less work.

[1] https://docs.gtranslate.io/en/articles/1348921-how-to-edit-t...

It is a metasyntactic variable for FNORD [1]. You have stumbled on the core of the Mother of All Conspiracy Theories, this is how they manipulate us all. Burn it I say, burn it with fire and spread the ashes.

[1] https://en.wikipedia.org/wiki/Fnord

Wow I thought the author just forgot to go back and replace these placeholders once they confirmed the right number but you're right, Google shows all kinds of articles across the internet referring to the XNUMXth century, what the heck?

https://www.google.com/search?q=xnumxth

Seems to be related to wordpress and working with translations. Haven't been able to pin if it is wordpress core related, or specific plugins. When you find those results on google, all the sites I saw it on were using wordpress.

It seems like a missing placeholder?

There's one report of this for the Polylang plugin [0]

And another reference in another plugin's help docs [1]

[0] https://wordpress.org/support/topic/i-have-some-error-with-t...

[1] https://docs.gtranslate.io/en/articles/1348921-how-to-edit-t...

> A rich deposit of follis dating back to the first half of the XNUMXth century AD was discovered in the sea of the north-eastern coast of Sardinia, in the territory of Arzachena.

Did they forget the variable $NUM? lol.

XNUMX looks like a placeholder for a number you'd find in a document where the actual number is supposed to be inserted later.

There might be a glitch or it's just a weird coincidence